This invention relates to a method and an apparatus for controlling fuel exchange and more particularly to refuelling control method and apparatus suitable for manipulating a plurality of fuel grippers.
In a prior art atomic power plant, upon exchange of atomic fuel, the atomic fuel is transferred between a reactor core and a fuel storage pool by a single fuel gripper, as disclosed in JP-A-58-34392. To speed up the fuel transfer, the fuel gripper must therefore be operated at an increased speed but the speed of the fuel gripper is permitted to be increased within only a limited range because the highest safety is required of the power plant. With the view of reducing the time required for transfer, JP-A-61-65192 and JP-A-61-149897 also propose a method which uses a refuelling machine having a plurality of grippers for gripping a plurality of fuel elements, whereby a plurality of fuel elements are gripped simultaneously and then transferred between a reactor core, hereinafter called a core, and a fuel storage pool (hereinafter called a pool).
In JP-A-61-65192, however, the simultaneity is only valid for the horizontal transfer between the pool and the core as well as for the horizontal motion in two directions namely, the X and Y directions, and, as a result, the effect of the paralleling (simultaneity) of operation is limited in part. However, JP-A-61149897, neither clearly describes the paralleling of operation nor discloses a specific means for realizing the parallel operation.
Thus, under the circumstances, it is desired that as many operations as possible be performed in parallel in order to efficiently effect fuel exchange. Actually, however, a space for mounting the refuelling machine is so limited that mounting of a plurality of, even only two, grippers is almost impossible if the grippers are perfectly mutual non-interfering. Accordingly, a technical task is to provide the manner of performing as many operations as possible by using a plurality of grippers which mutually impose constraint.